People expect to see replies in a comment chain because people expect the user to be notified. Nobody expects the user to follow down a totally different comment chain they weren't notified of to see every single insult anybody levies at them. And people recognize the extreme pettiness of baselessly insulting a user in a different comment chain where they aren't notified of the comment.
Whereas, if it's actually an informed response to misinformation, nobody sees it as petty, and it doesn't need to be in the same comment chain to have its effect, and it really doesn't need to be a back and forth.
Long comment chains really don't benefit anybody but the trolls who bait reasonable people into them, tbh.